I found many posts about running x11vnc at boot up on various flavors of Ubuntu 16.04 (Xenial Xerus). None of the posted suggestions would work for me as-is. I ended up finding a solution that works on Xubuntu 16.04 (Xenial Xerus), so am posting just the Systemd service file here as a suggestion of what works for me:

A very annoying problem came back to a Xubuntu 14.04 (Trusty Tahr) system quite suddenly and annoyingly would not go away. This system would not obtain a DHCP address. The Network Manager tray icon was not even the "spinning" icon indicating it was trying to obtain an address from the DHCP server. I checked around the Internet for suggestions how to resolve this issue. Nothing we located and tested resolved the issue.

I found myself trapped within a Vinagre Remote Desktop Viewer VNC session to a remote Linux server console. Trying all keys to find the magic key to pop mouse control back to my local Linux system, finally I found it: the F10 key! In the mean time, I had found the key to make the Vinagre on-line help come up, was navigating through it using keyboard only... and what few help suggestions there were, they always told to go to the Vinagre menu to click on something...

There seems to be a bug in Ubuntu in that when you reboot the system all remote CUPS printer connections are forgotten. This sounded like something needing a bit of scripting magic, so I went searching for how to accomplish that. Turns out it was quite simple actually. The utility lpadmin will be your friend to command line administer printers / print queues. The first lpadmin command attaches to the CUPS shared network printer queue via the IPP protocol, and the second lpadmin command sets the printer as the system default.